Yves Klein was a leader of the Nouveau réalisme movement, and considered an important figure in post-war European art. Klein was a pioneer in the development of Performance art, and is seen as an inspiration to and as a forerunner of Minimal art. His short career was characterized by many radical gestures, often touched with his flair for spectacle.

His exhibition, 'Proposte Monocrome, Epoca Blu' (Proposition Monochrome; Blue Epoch) at the Gallery Apollinaire, Milan, (January 1957), featured 11 identical blue canvases, using ultramarine pigment suspended in a synthetic resin 'Rhodopas,' described by Klein as "The Medium." Discovered with the help of Edouard Adam, a Parisian paint dealer, the optical effect retained the brilliance of the pigment which, when suspended in linseed oil, tended to become dull. Klein later deposited a Soleau envelope for this recipe to maintain the "authenticity of the pure idea." This colour, reminiscent of the lapis lazuli used to paint the Madonna's robes in medieval paintings, was to become known as International Klein Blue. The paintings were attached to poles placed 20 cm away from the walls to increase their spatial ambiguities.

The show was a critical and commercial success, traveling to Paris, Düsseldorf and London. The Parisian exhibition, at the Iris Clert Gallery in May 1957, became a seminal happening. To mark the opening, 1001 blue balloons were released and blue postcards were sent out using IKB stamps that Klein had bribed the postal service to accept as legitimate. Concurrently, an exhibition of tubs of blue pigment and fire paintings was held at Galerie Collette Allendy.